OBJECTIVE: Development and validation of a questionnaire that measures patients' experiences of collaboration between general practitioners (GPs) and specialists. METHODS: A questionnaire was developed using the method of the consumer quality index and validated in a cross-sectional study among a random sample of patients referred to medical specialists in the Netherlands. Validation included factor analysis, ascertain internal consistency, and the discriminative ability. RESULTS: The response rate was 65% (1404 patients). Exploratory factor analysis indicated that four domains could be distinguished (i.e. GP Approach; GP Referral; Specialist; Collaboration). Cronbach's alpha coefficients ranged from 0.51 to 0.93 indicating sufficient internal consistency to make comparison of groups of respondents possible. The Pearson correlation coefficients between the domains were <0.4, except between the domains GP Approach and GP Referral. All domains clearly produced discriminating scores for groups with different characteristics. CONCLUSIONS: The Consumer Quality Index (CQ-index) Continuum of Care can be a useful instrument to assess aspects of the collaboration between GPs and specialists from patients' perspective. PRACTICE IMPLICATIONS: It can be used to give feedback to both medical professionals and policy makers. Such feedback creates an opportunity for implementing specific improvements and evaluating quality improvement projects.